Document Homebrew transition for Fizzy 4 (#176)

* Document Homebrew transition for Fizzy 4

* Clarify Fizzy 4 Homebrew command timing

Author: robzolkos

README.md

@@ -49,10 +49,22 @@ yay -S fizzy-cli
 ```
 
 **Homebrew (macOS):**
+
+Latest stable Fizzy 3.x is available from the original tap:
+
 ```bash
-brew install basecamp/tap/fizzy
+brew install robzolkos/fizzy-cli/fizzy-cli
 ```
 
+Fizzy 4 release candidates are available from [Releases](https://github.com/basecamp/fizzy-cli/releases).
+
+> [!WARNING]
+> The Basecamp Homebrew tap command is for Fizzy 4 stable once it is released. Release candidates are not published to Homebrew.
+>
+> ```bash
+> brew install --cask basecamp/tap/fizzy
+> ```
+
 **Scoop (Windows):**
 ```bash
 scoop bucket add basecamp https://github.com/basecamp/homebrew-tap